In the practice of hospital pharmacy it often is necessary to add aseptically to bags, containers, receptacles, etc. of a base liquid such as sterile water, saline solution, dextrose, etc., a medicinal additive such as an antibiotic, a chemotherapeutic agent, an anticoagulant (i.e., heparin) etc., to the liquid. Such additives usually are added by a pharmacist to the base liquid at a pharmacy, and, in a hospital pharmacy, usually are done in batches, e.g., thirty (30) containers at a time are filled with the additive.
This procedure commonly is termed an admixture and usually is done with a syringe. The usual procedure requires the pharmacist to insert the needle of the syringe into a container of the additive, pull back the plunger a precise predetermined distance, withdraw the needle from the additive container, insert the needle into a container of base liquid such as through a resealable port in a plastic bag, and depress the plunger to insert the additive into the container of base liquid followed by removing the needle from the container. This procedure is then repeated a number of times.
In addition to being subject to human error in pulling the plunger back the right distance each time, and in transferring the additive without substantial loss, there also is a strain imposed on the fingers of the operator (pharmacist) in manipulating the syringe, particularly if a large number of these admixtures are being prepared. Such strain and fatigue is known to lead to errors in admixture which result in discarding of the admixture if the error is detected. If the error is undetected, the patient receives inaccurate medication.
Although various syringe devices have been proposed for facilitating the charging of the syringe with a medicinal additive and the dispensing of same, none of these previous attempts at facilitating charging and dispensing have provided the accuracy required as well as relief of strain on the operator while at the same time enabling an operator simply, quickly and accurately to insert precise amounts of medicinal additive into containers of base liquid repetitively.